ISDS 361A FINAL EXAM 2026 QUESTIONS AND
SOLUTIONS RATED A+
✔✔Sources of Data - ✔✔a) Primary = the CLIENT
b) Secondary = all other sources which does NOT COME FROM THE client
✔✔Why random sampling? - ✔✔targets population and eliminates bias, but extremely
difficult to achieve.
✔✔Non-random sampling error - ✔✔the result of using a sampling method that is not
random, such as using a convenience sample or a voluntary response sample
✔✔selection bias - ✔✔A polling error in which the sample is not representative of the
population being studied, so that some opinions are over- or underrepresented
✔✔non-response bias - ✔✔Bias introduced into survey results because individuals
refuse to participate.
✔✔statistical ethics - ✔✔important to give the right direction to research so that it is
objective and reflects the truth
✔✔Histogram - ✔✔a bar graph depicting a frequency distribution
✔✔symmetry - ✔✔having the same shape, size, and position on both sides of a dividing
line
✔✔Skewness - ✔✔The extent to which cases are clustered more at one or the other
end of the distribution of a quantitative variable rather than in a symmetric pattern
around its center
negatively skewed: left side is higher
positively skewed: right side is higher.
✔✔Modality - ✔✔determined by the number of peaks it contains. Most distributions
have only one peak but it is possible that you encounter distributions with two or more
peaks.
✔✔Uni-modal - ✔✔Has only one most frequently occurring score.
✔✔bi-modal - ✔✔2 peaks
✔✔Multi-modal - ✔✔more than two modes
SOLUTIONS RATED A+
✔✔Sources of Data - ✔✔a) Primary = the CLIENT
b) Secondary = all other sources which does NOT COME FROM THE client
✔✔Why random sampling? - ✔✔targets population and eliminates bias, but extremely
difficult to achieve.
✔✔Non-random sampling error - ✔✔the result of using a sampling method that is not
random, such as using a convenience sample or a voluntary response sample
✔✔selection bias - ✔✔A polling error in which the sample is not representative of the
population being studied, so that some opinions are over- or underrepresented
✔✔non-response bias - ✔✔Bias introduced into survey results because individuals
refuse to participate.
✔✔statistical ethics - ✔✔important to give the right direction to research so that it is
objective and reflects the truth
✔✔Histogram - ✔✔a bar graph depicting a frequency distribution
✔✔symmetry - ✔✔having the same shape, size, and position on both sides of a dividing
line
✔✔Skewness - ✔✔The extent to which cases are clustered more at one or the other
end of the distribution of a quantitative variable rather than in a symmetric pattern
around its center
negatively skewed: left side is higher
positively skewed: right side is higher.
✔✔Modality - ✔✔determined by the number of peaks it contains. Most distributions
have only one peak but it is possible that you encounter distributions with two or more
peaks.
✔✔Uni-modal - ✔✔Has only one most frequently occurring score.
✔✔bi-modal - ✔✔2 peaks
✔✔Multi-modal - ✔✔more than two modes
